I'm looking to get some help finding registrations for some past flights I've taken. I'm in the process of compiling a database filled with all flights I've taken in the past, and I ran into a little bit of a roadblock with some flights. I've been using FlightDiary (now myFlightRadar24) to accomplish this.

To find registration numbers I didn't have, I've been using the BTS Airline Statistics database for my domestic U.S. flights. I've also used the Worldwide ACARS report database to find some international flights. However, after using these, I can't seem to find a few of them and I would love for someone to help or guide me in the right direction.

EK605 from KHI-DXB on 31 December 2008 - operated by Emirates A330-200

US3276 from SRQ-CLT on 13 March 2009 - operated by U.S. Airways (or subsidiary) Embraer 175

US3208 from CLT-SRQ on 18 March 2009 - operated by U.S. Airways (or subsidiary) Embraer 175

PK722 from JFK-LHE-KHI on 29 May 2010 - operated by Pakistan International Airlines Boeing 777-200

US4174 from PHL-ABE on 3 February 2011 - operated by U.S. Airways (or subsidiary) DH8X

US3609 from ABE-PHL on 6 February 2011 - operated by U.S. Airways (or subsidiary) DH8X

I apologize for the lengthy list, but I would greatly appreciate any help on these! I tried looking on the ACARS site for the international ones and the BTS site for the domestic ones, but I had no luck. Not sure if I'm using it correctly, so any advice or help would be greatly appreciated.

I sounds like you have explored all the right sources. I cannot think of anything else. You need to resign to the fact that you won't be able to find some of the flights.
For your international flights you may want to try to find the opposite direction rotation, e.g. for EK605 KHI-DXB, try to find EK604 DXB-KHI (on the same date or a day before, as appropriate).

I was flying BOG-FRA-ARN on LH543 on 11-JAN. The BOG-FRA flight was quite delayed due to late incoming flight (LH542) and I missed my connection, arrived to final destination 5h35min late.

LH claims weather was the issue (I assume they mean at FRA) and thus no compensation for the delay. Was wondering if anyone would shed some light on two things;

1) is really weather affecting a previous flight (even if it was directly before and I was flying from an outstation i.e. BOG-FRA..) possible to refer to as a reason for denying EU 261/2004 compensation? I seem to recall that it shouldn't be but can't find whatever info i recall on that....

2) was the weather really that bad at the time? The incoming flight (LH542) was scheduled to depart at 12:25 zulu and departed 16:09, METAR;